Well, I don't have any experience with the Pass XP 20, but I did go from another solid state preamp, (the Ayre K-1XE), before going to the (hybrid) VTL TL-6.5 Signature. It is a significant sonic upgrade, albeit not a huge one. (Given the esteem that the Ayre is held in, I was pleasantly surprised that the upgrade was so significant). Having those two 12AU7 tubes in the TL-6.5 really does help the soundstaging, and the background still is as quiet as the Ayre.The VTL is feature packed in comparison to the Ayre.I use this with my ASR Basis Exclusive phono preamp, and my (hybrid) Lamm M2.1 monoblock amps, and I love the synergy between them.I will probably keep the TL-6.5 for many years, much as I did my Ayre.

The only concern you might have is the size of the unit. It is very deep, as it barely fits in my stereo rack.I hope this helps.Good luck in your search.